WO2001059412A1

WO2001059412A1 - Rotating machine and method for recording vibrations

Info

Publication number: WO2001059412A1
Application number: PCT/EP2001/001143
Authority: WO
Inventors: David Regnery; Lutz Intichar
Original assignee: Siemens Aktiengesellschaft
Priority date: 2000-02-14
Filing date: 2001-02-02
Publication date: 2001-08-16
Also published as: EP1126254A1

Abstract

The invention relates to a rotating machine (10), comprising a housing (11) and a rotor (12), with rotating blades (14), the tips of which are connected together by a covering band (15). According to the invention, the covering band (15) is provided with a magnetically-perceptible marking (20), which is read by at least one sensor (18). The invention further relates to a method for the non-contact recording of vibrations, using a covering band (15) with said magnetic marking (20).

Description

description

Rotation machine unα / experienced for the detection of vibrations

The present invention relates to a rotary machine with a housing and a rotor accommodated in the housing, which is provided with a number of blades lying side by side in circumferential direction, the tips of which are connected to one another by a cover band. It further relates to a method for the contactless detection of vibrations of blades on a rotor in a rotary machine, the tips of which are connected to one another via a shroud.

Such a machine and such a non-contact method are from the article “A Review of Analysis Technologies for Blade Tip-Timmg Measurements * by S. Heath and M. Imregun, ASME publication 97-GT-218, presented at the International Gas Turbine & Aeroengme Congress & Exhibition, Orlando, Florida, June 2-5, 1997. This article describes a non-contact vibration detection using lasers for single blades without a cover sheet. Such a non-contact vibration detection is also known from US 4,790,189. The tips of the individual blades are detected by means of magnetic sensors.

The known rotary machines and methods enable a high-precision recording of the fly-by times of all blades of a stage of a rotary machine to be monitored. A geometry that is clearly assigned to the blade is required to record the time of the flyby, and this is always the case with free-standing individual blades. However, many blade designs include integral or applied cover bands to reduce aerodynamic losses. The term shroud is not to be understood as restrictive here, but serves as a collective term for all connections of blades to one another in the area of the tip. The geo- Metπe such a cover band is generally not structured in such a way that a sensor can read a sufficient signal for detecting blade vibrations.

It is possible to mechanically change the shroud, for example to apply ridges or to mill out corrugation. Such changes can impair the function of the cover tapes, impair their integrity or have an insufficient service life.

The object of the present invention is therefore to provide a rotary machine and a method which enable reliable, contactless detection of the vibrations of blades, the tips of which are connected to one another via a shroud.

Erf däßass this problem is solved in a rotary machine of the type mentioned in that the shroud is provided with a magnetically recognizable marking and at least em sensor is provided for reading this magnetically recognizable marking.

The magnetically recognizable marking according to the invention can be scanned without contact and provides a geometry that is clearly assigned to the blades. The vibrations of the individual blades can then be calculated from the signal read by the at least one sensor. Coils or Hall sensors can be used as suitable sensors.

Advantageous further developments and refinements of the invention emerge from the dependent claims.

The marking advantageously runs periodically in the circumferential direction of the shroud. This leads to a constantly repeating signal. Vibrations of the shroud in circumferential direction are reliably detected by a phase shift of the read signal.

In an advantageous further development, the marking is composed of individual, repeating sections. This enables simple and inexpensive production.

According to an advantageous embodiment, the marking changes continuously in the transverse direction of the shroud without any repetition in such a way that the sensor reads exactly the signal for each transverse position of the shroud. This change in the transverse direction marking enables a detection of vibrations of the shroud in the transverse direction. The marking has independent information components in the circumferential and transverse directions. Therefore, vibrations in the transverse direction and vibrations in the circumferential direction can be recognized independently of one another. The continuous change of the marking in the transverse direction without repetition ensures that vibrations present in the transverse direction and circumferential direction are also recognized as such.

The marking can be continuous or consist of separate segments. Depending on the boundary conditions, for example the speed of the rotor, a continuous marking or a marking made up of segments separated from one another is used.

In an advantageous first embodiment, the marking is made of one piece of material with the shroud. Such a marking can be produced by placing an electrically conductive wire in the desired shape on the surface of the cover band and applying a current surge. The effect can be enhanced by a magnetic feedback for the river. This marking can be produced quickly and inexpensively in practically any shape. The structural integrity and surface of the shroud remain completely unaffected. Instead of the electrical πsch conductive wires can also be used to temporarily fit suitably shaped electrical or permanent magnets.

According to an advantageous second embodiment, the marking has magnets attached to the shroud. These magnets can easily be retrofitted in existing rotary machines.

According to an advantageous further development, the magnets have recesses in the shroud and are attached to them. The insertion of the magnets in the recesses enables a continuous smooth surface of the cover tape.

Several sensors distributed over the circumference of the housing are advantageously provided. The use of multiple sensors increases accuracy and enables better vibration detection.

In an advantageous development, the rotor is provided with at least one indicator for determining its rotational position. A specific rotational position of the rotor is defined as the zero position via this indicator and an assigned signal generator. Starting from this zero position, the speed of the rotor and vibrations in the circumferential direction can be determined.

In the method according to the invention, to solve the problem, it is provided that the shroud be provided with a magnetic marking and this magnetic marking is read by at least one sensor.

With this method it is possible for the first time to magnetically record vibrations of blades, the tips of which are connected to each other via a shroud. The acquisition is contactless and is clear.

In an advantageous embodiment, the read signal is recorded with a predetermined ⁾ t_o t \> M _- ^■

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1 shows a longitudinal section through a rotary machine; Figure 2 shows a section along the line II-II;

FIG. 3 shows an enlarged representation of the detail X from FIG. 2;

Figure 4 is a schematic plan view of a cover band of the second embodiment with a first signal; FIG. 5 shows a view similar to FIG. 4 of a measurement displaced along a circumferential direction; and FIGS. 6 and 7 further configurations of a marking on the shroud.

FIG. 1 shows a longitudinal section through a turbine 10 with a housing 11 and a rotor 12. The housing 11 is provided with a row of guide vanes 13 and the rotor 12 carries a number of rotor blades 14. The tips of the rotor blades 14 are above a shroud 15 connected.

A fluid flows through the turbine 10 in the direction of the arrow 16, which rotates the rotor 12 m about an axis 29. The fluid flows along the guide vanes 13 and the rotor blades 14. To detect vibrations of the blades 14, the shroud 15 is provided with a magnetic marking 20. This marking 20 is read by sensors 18 in the housing 11.

To determine the rotational position of the rotor 12 em indicator 25 and e signal transmitter 26 are provided. With each revolution of the rotor 12, a signal is emitted by the signal generator 26. The rotational position of the rotor 12 can thus be clearly determined and linked to the signals from the sensors 18. The rotational position in which the indicator 25 lies opposite the signal transmitter 26 is advantageously set as the zero position for the rotor 12. The signal transmitter 26 also enables the speed of the rotor 12 to be determined. FIG. 2 shows a section along the line II-II in FIG. 1 and FIG. 3 shows an enlarged view of the detail X from FIG. 2. In the exemplary embodiment shown in FIGS. 2 and 3, the marking 20 of the cover tape 15 consists of a series of Magnets 17. These magnets 17 are inserted into recesses 19 of the cover tape 15 and fastened thereon. The result is an essentially smooth, continuous surface of the shroud 15.

To read the marking 20, a plurality of sensors 18 are provided, which are distributed over the circumference of the housing 11. The signals read by the sensors are linked to one another by a suitable data processing device, not shown in detail. The rotational position and speed of the rotor 12 are determined by means of the indicator 25 and the signal generator 26 and the signals from the sensors 18 are linked. By jointly evaluating the signals from the sensors 18 and the signal transmitter 26, vibrations of the moving blades 14 and the shroud 15 can be precisely detected.

Figures 4 and 5 show a cover tape 15 m of the settlement. A single continuous marking 20 is provided, which is essentially zigzag. The marking 20 is advantageously produced by placing an electrically conductive wire on the cover strip 15 and applying a current surge. It is designed gst piece with the shroud 15, so that the function of the shroud is not affected and the desired strength is maintained.

The marking 20 is formed periodically and continuously in the circumferential direction 28. It is composed of individual repeating sections. The magnetic alignment is shown schematically in FIGS. 4 and 5 by the book bars “N ^X and“ S. A complete change in the magnetic orientation from north pole to south pole is not necessary. Erfmdungsgemaß may be provided to a weaker North Pole also a change from a strong magnetic north pole ^¬. In this embodiment, the soles of the magnetic marking are arranged radially inward in the direction of the axis 29. Of course, the south poles can also be provided as a marking and the north poles can be offset in the direction of the axis 29.

During operation of the turbine 10, vibrations of the rotor blades 14 can occur both in the transverse direction 27 and in the circumferential direction 28. The measurement takes place approximately along a circumferential line 30. FIG. 4 shows a measurement in a first transverse position of the shroud 15 and FIG. 5 shows a measurement in a second transverse position. The read signal 22a, 22b is shown below the development of the cover tape 15. The time t is plotted on the abscissa and the magnetic field strength H is plotted on the ordinate. Of course, the circumferential angle or another suitable unit can also be used instead of the time t.

During operation of the turbine 10, a periodically repeating signal 22 results. The indicator 25 and the signal transmitter 26 define a new zero point for each revolution of the rotor 12. When vibrations of the rotor blades 14 and the shroud m the circumferential direction 28 15 enters a phase ^¬ shift of the signal 22 along the abscissa. This phase shift is recognized and enables the oscillation state of the rotor blades 14 to be inferred.

In the case of vibrations in the transverse direction 27, the position of the circumferential line 30, along which the measurement is taken, changes with respect to the marking 20. A different signal 22b results accordingly. To detect vibrations, the two read signals 22a, 22b are compared with one another. M may both signals 22a, 22b entha ¹ ene static proportions, for example due to thermal expansion of the rotor 12 overall genuber the housing 11, cancel each other out in the evaluation. By comparing the signal 22b with the previously read signal 22a, all the vibrations of the shroud 15 and thus of the blades 14 are thus detected.

The signal 22a serving as the reference signal can be continuously redefined, for example, with each revolution of the rotor 12. Alternatively, a reference signal can be used which is not changed over several revolutions or longer periods. Vibrations of the blades 14 are also reliably detected in this case. At the same time, static displacements between the housing 11 and the rotor 12 can be detected.

In extreme cases, a reference signal is used, which is specified once and is not subsequently changed. A comparison of the read signal 22a, 22b with this reference signal provides information about both static displacements and vibrations.

Vibrations in the transverse direction 27 and in the circumferential direction 28 can be present at the same time. These vibrations must also be reliably detectable. The marking 20 is therefore designed such that it changes continuously in the transverse direction of the shroud 15 without repetition such that the sensors 18 read exactly e signal 22 for each transverse position of the shroud 15. The marking 20 thus contains a first piece of information for the transverse direction 27 and a second piece of information for the circumferential direction 28. These two pieces of information can be read separately and independently of one another. What is essential for this is the continuous change of the marking 20 m transverse direction of the shroud 15 without repetition. If, for example, parallel lines of the same thickness are used as the marking 20, there is no change in the transverse direction 27 of the cover tape 15. Such a marking would therefore only enable the detection of vibrations in the transverse direction 27 or in the circumferential direction 28. Vibrations that occur both in the transverse direction 27 and in the circumferential direction 28 can no longer be reliably detected with such a marking.

FIGS. 6 and 7 show further possible configurations of markings 20. FIG. 6 shows essentially wedge-shaped magnets 17, which are inserted at a distance from one another in the recesses 19 of the shroud 15. The magnets 17 advantageously have a constant distance.

Vibrations in the transverse direction 27 are detected via the wedge shape of the magnets 17, while vibrations in the circumferential direction 28 are detected via a phase shift.

Alternatively, a marking 20 made up of individual, separate segments 23, 24 according to FIG. 7 can be used. The segments 23, 24 are arranged at repeating distances 21 and periodically in the circumferential direction 28 of the shroud 15. The phase shift of the signal 22 is in turn used to detect vibrations in the circumferential direction 28. Vibrations in the transverse direction 27 are detected over the changing distance between the segments 23, 24. These markings 20 are also linked to the output signal of the signal transmitter 26 for detecting the speed and rotary bearing of the rotor 12.

The invention provides a rotary machine and method which enable reliable, non-contact detection of the vibrations of rotor blades 14 with a shroud 15. The detection takes place by means of a magnetically recognizable marking 20 on the cover band. This marking 20 is advantageous in the circumferential direction 28 of the shroud. Disch and changes continuously in the transverse direction 27 without repetition. Vibrations in the transverse direction 27 and in the circumferential direction 28 can thus be detected separately from one another.

Claims

claims

1. Rotary machine with a housing (11) and a m housing (11) accommodated rotor (12) which is provided with a number of blades (14) lying next to one another in the circumferential direction, the tips of which are connected to one another via e shroud (15) characterized in that the cover band (15) is provided with a magnetically recognizable marking (20) and at least one sensor (18) is provided for reading this magnetically recognizable marking (20).

2. Rotary machine according to claim 1, characterized in that the marking (20) n circumferential direction (28) of the shroud (15) runs periodically.

3. Rotary machine according to claim 1 or 2, characterized in that the marking (20) from individual, repeating sections (21) is composed.

4. Rotary machine according to one of claims 1 to 3, characterized in that the marking (20) m transverse direction (27) of the shroud (15) changes continuously without repetition such that the sensor (18) to each transverse position of the shroud (15) reads exactly one signal (22).

5. Rotary machine according to one of claims 1 to 4, characterized in that the marking (20) is continuous or consists of separate segments (23, 24).

6. Rotary machine according to one of claims 1 to 5, characterized in that the marking (20) is made of material with the shroud (15).

7. Rotary machine according to one of 7Λnspruche 1 to 5, characterized in that the marking (20) on the shroud (15) has magnets (17) attached.

8. Rotary machine according to claim 7, characterized in that the magnets (17) in recesses (19) of the shroud (15) are inserted and fastened therein.

9. Rotary machine according to one of claims 1 to 8, characterized in that a plurality of sensors (18) distributed over the circumference of the housing (11) are provided.

10. Rotary machine according to one of claims 1 to 9, characterized in that the rotor (12) is provided with at least one indicator (25) for determining its rotational position.

11. A method for the contactless detection of vibrations of blades (14) on a rotor (12) in a rotary machine (19), the tips of which are connected to one another via a shroud (15), characterized in that the shroud (15) with a magnetic Provide marking (20) and this magnetic marking (20) is read via at least one sensor (18).

12. The method according to claim 11, characterized in that for the detection of vibrations of the blades (14) the read signal (22) is compared with a predetermined reference signal.

13. The method according to claim 12, characterized in that a fixed predetermined signal or a previously read signal (22) is used as the reference signal.

14. The method according to any one of claims 11 to 13, characterized in that a plurality of sensors (18) are used and the signals (22) read from the sensors (18) are linked to one another for detecting the vibrations.

15. The method according to any one of claims 11 to 14, characterized in that the rotational position of the rotor (12) is determined via a signal transmitter (26) and is linked to the signals (22) of the at least one sensor (18).